diff --git a/evals/eval.py b/evals/eval.py
index 094e58b9ad..b1d1acc1e3 100644
--- a/evals/eval.py
+++ b/evals/eval.py
@@ -68,6 +68,7 @@ def __init__(
         self.registry = registry or Registry()
         self.samples_jsonl = samples_jsonl
 
+    @abc.abstractmethod
     def eval_sample(self, sample: Any, rng: random.Random):
         raise NotImplementedError()